1 /* Copyright 2022-2025 Thales Alenia Space
2 * Licensed to CS GROUP (CS) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * CS licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.orekit.estimation.measurements.gnss;
18
19 import java.util.Arrays;
20
21 import org.hipparchus.analysis.differentiation.Gradient;
22 import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
23 import org.hipparchus.geometry.euclidean.threed.Vector3D;
24 import org.orekit.estimation.measurements.EstimatedMeasurement;
25 import org.orekit.estimation.measurements.EstimatedMeasurementBase;
26 import org.orekit.estimation.measurements.ObservableSatellite;
27 import org.orekit.estimation.measurements.QuadraticClockModel;
28 import org.orekit.propagation.SpacecraftState;
29 import org.orekit.time.AbsoluteDate;
30 import org.orekit.utils.Constants;
31 import org.orekit.utils.FieldPVCoordinates;
32 import org.orekit.utils.PVCoordinates;
33 import org.orekit.utils.PVCoordinatesProvider;
34 import org.orekit.utils.ParameterDriver;
35 import org.orekit.utils.TimeSpanMap.Span;
36 import org.orekit.utils.TimeStampedPVCoordinates;
37
38 /** One-way GNSS range rate measurement.
39 * <p>
40 * This class can be used in precise orbit determination applications
41 * for modeling a range rate measurement between a GNSS satellite (emitter)
42 * and a LEO satellite (receiver).
43 * <p>
44 * The one-way GNSS range rate measurement assumes knowledge of the orbit and
45 * the clock offset of the emitting GNSS satellite. For instance, it is
46 * possible to use a SP3 file or a GNSS navigation message to recover
47 * the satellite's orbit and clock.
48 * <p>
49 * This class is very similar to {@link InterSatellitesOneWayRangeRate} measurement
50 * class. However, using the one-way GNSS range measurement, the orbit and clock
51 * of the emitting GNSS satellite are <b>NOT</b> estimated simultaneously with
52 * LEO satellite coordinates.
53 *
54 * @author Luc Maisonobe
55 * @since 12.1
56 */
57 public class OneWayGNSSRangeRate extends AbstractOneWayGNSSMeasurement<OneWayGNSSRangeRate> {
58
59 /** Type of the measurement. */
60 public static final String MEASUREMENT_TYPE = "OneWayGNSSRangeRate";
61
62 /** Simple constructor.
63 * @param remote provider for GNSS satellite which simply emits the signal
64 * @param dtRemote clock offset of the GNSS satellite, in seconds
65 * @param date date of the measurement
66 * @param rangeRate observed value
67 * @param sigma theoretical standard deviation
68 * @param baseWeight base weight
69 * @param local satellite which receives the signal and perform the measurement
70 */
71 public OneWayGNSSRangeRate(final PVCoordinatesProvider remote,
72 final double dtRemote,
73 final AbsoluteDate date,
74 final double rangeRate, final double sigma,
75 final double baseWeight, final ObservableSatellite local) {
76 this(remote, new QuadraticClockModel(date, dtRemote, 0.0, 0.0), date, rangeRate, sigma, baseWeight, local);
77 }
78
79 /** Simple constructor.
80 * @param remote provider for GNSS satellite which simply emits the signal
81 * @param remoteClock clock offset of the GNSS satellite
82 * @param date date of the measurement
83 * @param rangeRate observed value
84 * @param sigma theoretical standard deviation
85 * @param baseWeight base weight
86 * @param local satellite which receives the signal and perform the measurement
87 * @since 12.1
88 */
89 public OneWayGNSSRangeRate(final PVCoordinatesProvider remote,
90 final QuadraticClockModel remoteClock,
91 final AbsoluteDate date,
92 final double rangeRate, final double sigma,
93 final double baseWeight, final ObservableSatellite local) {
94 // Call super constructor
95 super(remote, remoteClock, date, rangeRate, sigma, baseWeight, local);
96 }
97
98 /** {@inheritDoc} */
99 @Override
100 protected EstimatedMeasurementBase<OneWayGNSSRangeRate> theoreticalEvaluationWithoutDerivatives(final int iteration,
101 final int evaluation,
102 final SpacecraftState[] states) {
103
104
105 final OnBoardCommonParametersWithoutDerivatives common = computeCommonParametersWithout(states, false);
106
107 // Estimated measurement
108 final EstimatedMeasurementBase<OneWayGNSSRangeRate> estimatedRangeRate =
109 new EstimatedMeasurementBase<>(this, iteration, evaluation,
110 new SpacecraftState[] {
111 common.getState()
112 }, new TimeStampedPVCoordinates[] {
113 common.getRemotePV(),
114 common.getTransitPV()
115 });
116
117 // Range rate value
118 final PVCoordinates delta = new PVCoordinates(common.getRemotePV(), common.getTransitPV());
119 final double rangeRate = Vector3D.dotProduct(delta.getVelocity(), delta.getPosition().normalize()) +
120 Constants.SPEED_OF_LIGHT * (common.getLocalRate() - common.getRemoteRate());
121
122 // Set value of the estimated measurement
123 estimatedRangeRate.setEstimatedValue(rangeRate);
124
125 // Return the estimated measurement
126 return estimatedRangeRate;
127
128 }
129
130 /** {@inheritDoc} */
131 @Override
132 protected EstimatedMeasurement<OneWayGNSSRangeRate> theoreticalEvaluation(final int iteration,
133 final int evaluation,
134 final SpacecraftState[] states) {
135
136 final OnBoardCommonParametersWithDerivatives common = computeCommonParametersWith(states, false);
137
138 // Estimated measurement
139 final EstimatedMeasurement<OneWayGNSSRangeRate> estimatedRangeRate =
140 new EstimatedMeasurement<>(this, iteration, evaluation,
141 new SpacecraftState[] {
142 common.getState()
143 }, new TimeStampedPVCoordinates[] {
144 common.getRemotePV().toTimeStampedPVCoordinates(),
145 common.getTransitPV().toTimeStampedPVCoordinates()
146 });
147
148 // Range rate value
149 final FieldPVCoordinates<Gradient> delta = new FieldPVCoordinates<>(common.getRemotePV(), common.getTransitPV());
150 final Gradient rangeRate = FieldVector3D.dotProduct(delta.getVelocity(), delta.getPosition().normalize()).
151 add(common.getLocalRate().subtract(common.getRemoteRate()).multiply(Constants.SPEED_OF_LIGHT));
152 final double[] rangeRateDerivatives = rangeRate.getGradient();
153
154 // Set value and state first order derivatives of the estimated measurement
155 estimatedRangeRate.setEstimatedValue(rangeRate.getValue());
156 estimatedRangeRate.setStateDerivatives(0, Arrays.copyOfRange(rangeRateDerivatives, 0, 6));
157
158 // Set first order derivatives with respect to parameters
159 for (final ParameterDriver measurementDriver : getParametersDrivers()) {
160 for (Span<String> span = measurementDriver.getNamesSpanMap().getFirstSpan(); span != null; span = span.next()) {
161
162 final Integer index = common.getIndices().get(span.getData());
163 if (index != null) {
164 estimatedRangeRate.setParameterDerivatives(measurementDriver, span.getStart(), rangeRateDerivatives[index]);
165 }
166 }
167 }
168
169 // Return the estimated measurement
170 return estimatedRangeRate;
171
172 }
173
174 }